1. Field of the Invention
The present invention relates to an improved method of encoding computer-generated image sequences, and more particularly to the use of prototypes for encoding how portions of a video stream are to be quantized, animated or otherwise updated.
2. Discussion of the Background
Although many computer-generated images were previously generated by specifying every pixel in every frame together, modern computer image sequences often are created by merging plural multimedia objects (e.g., video and 2D- or 3D- graphics primitives)--sometimes with one or more sound tracks. In the area of multimedia, images and/or scenes are composed using a language. For instance, the HyperText Markup Language (HTML) specifies the two-dimensional (2D) composition of text and graphics. Similarly, the Virtual Reality Markup Language (VRML) describes three-dimensional (3D) worlds.
Multimedia languages also now include extensions for dynamic alteration of the composed images. HTML now includes Dynamic HTML (DHTML) extensions, such as are described in Dynamic HTML: The Definitive Reference, by Danny Goodman, published by O'Reilly & Associates, Inc., 1998, the contents of which are incorporated herein by reference. Moreover, XML extensions for HTML provide a meta-language to describe how the native language is to be modified or extended.
Similarly, VRML includes support for "PROTO" definitions which enable new primitives to be "prototyped." Part of a definition is a code block or plural code blocks that are executed by the VRML environment to provide the newly prototyped functionality.
The Motion Pictures Expert Group (MPEG) was formed to investigate the technologies required for the encoding and decoding of image streams. The resulting standard (now referred to as "MPEG-1") has served as a basis for two additional MPEG standards: MPEG-2 and MPEG-4. MPEG-4 is a standard that is "in progress." The final committee drafts are ISO/IEC FCD 14496-1 MPEG-4 Systems and -2 MPEG-4 Visual, the contents of the final committee drafts are incorporated herein by reference. Those drafts include various methods of encoding multimedia content. Such methods include: (1) quantization methods for scene parameters, (2) animation streams for encoding and transmitting multimedia scenes, and (3) update streams to modify the multimedia information over time. The finalized draft of MPEG-4 includes support for: (1) quantization in Binary Format for Scenes (hereinafter "BIFS"), (2) animation using BIFS (hereinafter "BIFS-Anim") and (3) update control using BIFS (hereinafter "BIFS-Command").
Using quantization under BIFS includes tagging nodes and fields with a quantization category. Each field of each node is assigned a quantization category, which is applied to the field when it is given a quantization parameter structure to parameterize during the quantization process.
BIFS-Anim defines an encoding method for streaming- and file-based animation of multimedia data. BIFS-Anim includes 3 basic components: (1) a scene graph, (2) an animation mask, and (3) animation frames. The scene includes (a) untagged objects that are static and (b) tagged objects that are to be modified. The animation mask sets the properties of the tagged objects that are to be modified by the animation stream.
The BIFS Command is a protocol to update BIFS nodes and a scene graph. It enables the transportation of changes to the scene by sending commands to replace the whole scene with another one, removing some of the tagged objects, or changing values of properties of tagged objects in the scene. cl SUMMARY OF THE INVENTION
It is an object of the present invention to provide dynamic programming interfaces and/or extensions for a multimedia content lagnguage and/or a multimedia placement language.
It is a further object of the present invention to provide links to animation, modification and quantization methods and to provide new prototypes for scenes, such that scenes can be represented, animated and modified efficiently.
This and other objects of the present invention are addressed by one or more of (1) a computer-implemented method for encoding multimedia content using dynamic interfaces, (2) a system for encoding multimedia content using dynamic interfaces, and (3) a computer program product for encoding multimedia content using dynamic interfaces.